Processes for producing modified cellulosic textile materials



United States Patent 3,194,627 PRGQIESSES FOR PRODUCENG MODEFKEDCELLUZLOSEC TEXTILE MATERHAIS Dmitry Michael Gagarine, Pendleton, S.C.,assignor to Deer-tug Millikan Research (Importation, Pendleton,

S.C., a corporation of Delaware No Drawing. Filed Aug. 7, 1958, Ser. No.753,620

17 Claims. (til. 8-416) Patent No. 2,985,501.

According to the disclosure of application SN. 575,-

716, now Patent N 0. 2,985,501, a cellulosic material is impregnatedwith an aqueous basic solution and reacted with a cross-linking agentunder such conditions that the product has a pronounced wet memory andwill, when wet, tend to assume the configuration imparted during thecrosslinking reaction. It is normally a characteristic of the processesdisclosed in application S.N. 575,716, new Patent No. 2,985,501, as wellas certain other processes wherein a cellulosic material is reacted witha cross-linking agent in the presence of a base, that the productsthereof have, in each instance, a wet tensile strength which is lowerthan the dry strength of the product and this is disadvantageous for thereason that textile materials produced by these processes are, whilewet, frequently subjected to considerable stress during washing.

According to the improved process of this invention, fabrics and yarnshaving Wet strengths approximately equal to their dry strengths areproduced by applying to a cellulosic material, in addition to a basicsolution and a cross-linking agent, a small quantity of an anti-oxidantmaterial or composition.

It is quite surprising for two reasons that by the simple expedient ofapplying an antioxidant the wet strengths of textile materials processedaccording to the above-mentioned procedures can be increased withoutmaterially affecting the dry strengths thereof. First, it would normallybe assumed that any damages due to oxidation in processes of this typewould equally affect the wet and dry strengths and that theunproportional reduction in wet strength could not be due to this cause.Second, the reaction conditions and reagents in these processes are suchthat no appreciable degree of oxidation damage would be expected and inother processes where a fabric or yarn is impregnated with an alkalinesolution under similar conditions, no noticeable degree of oxidationdamage is normally encountered. Further, the crosslinking agentsemployed according to this invention are not known to be oxidizingagents and normally do not act as such. In other words, it isapparentlyonly under the specific conditions present in processes asabove de scribed that one experiences, in the absence of an antioxidant,this unusual type of damage which results in a reduction in wet strengthwithout a corresponding reduction in dry strength.

The cross-linking agents which can be employed in the improved processof this invention are those capable of being represented by one of thefollowing formulae:

in in la 1's wherein R and R in each instance, represent hydrogen or amonovalent, nonfunctional radical, and X represents halogen. When across-linking compound corresponding to one of the above formulaecontains two Z groups, the groups may be the same or different.

R R R R and R in the above formulae, in each instance, preferablyrepresent hydrogen since such compounds are the most readily prepared,but they can in one or more instances represent lower alkyl groups suchas methyl or ethyl; hydroxyalkyl groups such as hydromethyl orhydroethyl; monocyclic aryl groups such as phenyl or tolyl; cycloalkylgroups such as cyclohexyl; haloalkyl groups such as chloromethyl andchloroethyl; or R and R can together represent a divalent connectingradical such as a methylene or an ethylene radical. The only requirementis that R R R R and R must not be such as to prevent the compound fromreacting with at least one hydroxy group in two different cellulosemolecules.

R in the above formulae can represent any divalent connecting group, butin most instances will represent either an alkylene group such asmethylene, ethylene, or propylene; a hydroxyalkylene group such ashydroxypropylene; or a group of the formula wherein Y represents oxygenor sulfur, R-and R" represent lower alkylene groups such as methylene orethylene and R represents any divalent connecting radical as illustratedby a lower alltylene group, a lower hydroxyalkylene group such asZ-hydroxypropylene, a monocyclic aryl radical such as phenylene ortoluylene, a radical of the formula C l-l.,(O-C H wherein n is aninteger of from 1 to about 20; or a radical of the formula (I)H (n'"oo11 011- 0 H2 0) ,,R- wherein n represents an integer of from 1 to about5 and R represents a divalent hydrocarbon radical as illustrated byCompounds of the latter type (i.e. containing a R-YR'-Y'R"- group)result when epichloro hydrin or divinylsulfone is reacted with less thanan equal molar quantity of a dillydric alcohol or phenol.

The cross-linking agent should in all instances be such that it resultsin linkages having a chain length of from 3 to 24 carbon atoms andshould preferably be such that it results in linkages of from 3 to 10carbon atoms in length. Specific illustrative examples of suitablecrosslinking compounds are: epichlorohydrin, 1,3-dich1oro- 2-propanol,2,3-dichloro-1-propanol, 2,3-dibromo-1-propanol, m-di(fi-epoxypropoxy)benzene, 1,3-di(;3-hydroxylinking reaction.

y-chloropropoxy) -2-propanol, 1,2-di (ti-hydroxy-v-chloropropoxy)ethane, 1,2-di(/3, -epoxypropoxy) ethane, l,2;3,4'-diepoxybutane,1,2;5,6-diepoxyhexane, 1,5-dih droxy-2,4-dichloro-cyclohexane and2,6-dichloro-3,4,5- trihydroxy 5 hydroxymethylheptane. cross-linkingcompounds are l,3-dichloro-2-propanol, 2,3- dichloro-l-propanol, andmixtures of the two.

The amount of the cross-linking agent employed may be varied within widelimits under certain conditions, but an amount of the cross-linkingagent equal to from about 6% to 30% of the weight of cellulosic fibersis usually satisfactory and from 8% to by weight of. the cellulosicfibers, of the cross-linking agent ispreferred;

This generally results in the cellulosic fibers gaining from about 2%to'4% in weight.

The basic solution to be employed with the process of this invention canbe a solution of any of the wellknown strongly basic inorganic ororganic materials. Preferably solutions of an alkali metal hydroxidesuch as sodium hydroxide or potassium hydroxide are employed, butsolutions of other bases such as sodium silicate, and quaternaryammonium bases such as tri methylphenylammonium hydroxide and tetramethylammonium hydroxide can also be used. The amount of the basicsolution employed should generally be suflicient to provide an amount ofwater in the fabric equal to from 15% to 130% of dry fabric or yarnweight and preferably from 60% to 90% of dry fabric or yarn weight, andthe effective concentration of the basic solution in the fabric or yarnshould be from about 3% to and preferably from 5% to 15% by weight.

The process of this invention for forming flat-drying textile materialscan be satisfactorily performed with yarns or fabrics containing eithernatural cellulose fibers, re generated cellulose fibers, or modifiedcellulose fibers having a portion of the hydroxy groups therein blockedby ester or ether groups. Examples of materials of the latter type whichcan be employed include yarns or fabrics composed of cellulose acetate,cellulose butyrate, ethyl cellulose or methyl cellulose fibers.Generally, the cellulosic fibers should have an average of at leastabout 1.8 free hydroxy groups per glucose unit, and cellulosic materialshaving a smaller number of free hydroxy groups do not normally givesatisfactory results, even though, in the case of cellulose esters, theester groups might theoretically be removed by hydrolysis during thecross yarns and fabrics formed from cellulose derivatives as abovedescribed, it finds its greatest utility with fibers and fabrics formedof unmodified cellulose and'particularly with cotton materials.

Satisfactory results, according to this invention, can also be achievedwith yarns or fabrics partially composed of other than cellulosicmaterials, and this is particularly true if the non-cellulosic fibershave some flatdrying properties of their own., For example, theflatdrying tendencies of a yarn spun from a mixture of glycol Thepreferred While the invention is operable with hydroquinone andpyrogallol; aromatic amines, such as aniline; aliphatic amines, such asoctadecylarnine; and condensation products of amines and aldehydes, suchas the condensation product of aniline and croton aldehyde.Sodiumsulfite is generally the preferred antioxidant for use accordingto this invention for the reasons, among others that it is inexpensive,is readily soluble in basic solutions, and does not discolor in theprocess,

The amount of the antioxidant employed can be varied within reasonablywide limits, but as a general rule the amount employed should be equalto at least about 0.005% of the Weight of basic solution withwhich thecellulosic material is impregnated and in most instances better resultsare achieved if the amount of antioxidant material is at least 0.01% ofthe Weight of basic solution. A considerable excess over theminimumrequired can be employed, but in most instances the nature of thecrosslinking agent is such that a reaction With the anti oxidant ispossible andthe use of large excesses of the antioxidant should beavoided. For this and other reasons it is seldom if ever advantageous toemploy more than about 8% of the antioxidant, based upon the weight ofthe basic solution, and in most instances no improvement is obtained byemploying more than 3.0% of the antioxidant material. a

The cross-linking agent and basic solution may be applied in anysuitable manner as illustrated by padding, spraying, brushing or thelike. If the basic solution is to be applied first to either a wetor drytextile material, best results are usually obtained by immersing thefabric or yarn in a solution of the base and thereafter passing H v ofits surface in contact with a supply of the solution and the antioxidantmay be either organic or inorganic aldehydes, such as glucose; aromaticalcohols, such as to be applied. This eliminates the possibility that alarge percentage of the cross-linking. agent might be leached from thetextile material and results in less hydrolysis of the cross-linkingagent that might be obtained by dipping the fabric or yarn into a largevolume of the basic solution. The cross-linking agent is in almost allinstances best applied by means ofran applicator roll'because of therelatively small quantity of the agent which need be employed andbecause this method of application generally results in greateruniformity than spraying.

The most advantageous procedure for applying the antioxidant material tothe yarn or fabric comprises adding the same to the basic solution withwhich'the fabric or yarn is to be impregnated, since such a procedureadds no additional manipulative steps to the process, insures that theantioxidant material is present at all times while the fabric or yarn isin contact with the. basic solution and insures an even distribution ofthe antioxidant material; The antioxidant can, however, be applied bypadding the fabric or yarn through a solution of the antioxidant or byspraying a solution of the antioxidant onto the fabric or yarn prior tothe time that a it is impregnated withthe alkaline solution. When thecross-linking. agent is applied to the textile material prior to theapplication of the basic solution it may be advantageous to apply anantioxidant with the cross-linking agent, and this is sometimes trueeven though an antioxidant is also applied with the basic solution. Inapplying an antioxidant with the cross-linking agent, the mostconvenient procedure comprises dissolving the antioxidant in thereagent, but it will be understood that thisrequires the use of anantioxidant which is soluble in the particular cross-linking agent beingapplied to the cellulosic material.

The cross-linking reaction .tends to permanently fix the configurationof the fabric or yarn as that prevailing during the reaction. In otherwords, if one desires a fabric that will have a flat and pressedappearance after Washing, it is necessary that the fabric be retained ina flat condition during the cross-linking reaction. This can beaccomplished by conducting the reaction while the fabric is in a tenterframe or by rolling the same into a tight roll. If desired, the roll offabric can be wrapped in a water impervious cover, such as aluminum foilor a sheet of vinyl plastic, as illustrated by polyethylene plastic. Ofcourse, if it is desired that the fabric display permanent pleats or thelike, then it is necessary that the cross-linking reaction be conductedwhile the fabric is in a pleated condition.

The cross-linking reaction may be conducted at any suitable temperaturebelow about 110 C. or the boiling point of the basic aqueous solution atthe particular pressure under which the reaction is conducted, but forreasons of convenience, the reaction is preferably carried out at roomtemperature or the temperature naturally resulting from the reaction.The cross-linking reaction is slightly exothermic and, in mostinstances, will cause a gradual rise in temperature as the reactionprogresses, but this is not generally detrimental and no means forretaining the reaction temperature at a constant level are generallynecessary. The time required for the cross-linking reaction will varysomewhat with the temperature, the cross-linking agent employed and theorder in which the reagents are applied, but even at low temperatures,i.e. 20 C. to 30 0, good fiatdrying properties are normally obtained in24 hours or less, and at 75 C., the reaction is, as a rule, reasonablycomplete in 20 minutes or less. Exceedingly long reaction times, forexample, forty-eight hours or more, can be employed, but thecross-linking reaction is preferably allowed to continue for only solong as is necessary to obtain satisfactory flat-drying properties.

The invention will now be more specifically illustrated by the followingexamples in which all parts are by weight unless otherwise indicated:

Example I A length of cotton sheeting previously singed, clesized,bleached, and frame dried is passed into a solution of 14% sodiumhydroxide and squeezed to remove excess liquid so that the total pick-upof sodium hydroxide solution is approximately 90% of the dry weight ofthe fabric. The alkaline fabric is then passed over an applicator rollby means of which there is applied 11%, based on the dry fabric weight,of a mixture of 1,3-dichloropropanol-Z, and 2,3-dichloropropanol-l inapproximately equal parts by weight, and the fabric is thereafter rolledinto a tight roll and allowed to remain for approximately hours. Thefabric is then unrolled, washed to remove unreacted reagents and dried.

A fabric processed according to this example was found to have a drytensile strength of 32.7 pounds warpwise and 26.5 pounds fillingwise anda Wet tensile strength of 23 pounds warpwise and 18 pounds fillingwise.

Example II Example I is repeated except that to the alkali solutionthere is added 0.05 based on the weight of solution, of anhydrous sodiumsulfite.

A sample of fabric processed according to the procedure of this examplewas found to have a dry tensile strength of 33 pounds warpwise and 26pounds fillingwise and a Wet tensile strength of 28 pounds warpwise and22 pounds fillingwise so that there was more than a 20% improvement inboth warp and filling wet tensile strength as compared to the resultsobtained in the procedure of Example 1.

Example III Example 11 is repeated except that an equal weight of sodiumthiosulfate is substituted for the sodium sulb tially the same as areobtained by the procedure of Example II.

The procedure is the same as illustrated in the above examples whenemploying other cross-linking agents, bases, antioxidants and types oftextile materials.

Having thus described my invention and two specific embodiments thereof,What I desire to claim and secure by Letters Patent is:

1. In a process for imparting fiat drying characteristics to a textilematerial containing cellulosic fibers having an average of at leastabout 1.8 free hydroxyl groups per glucose unit, wherein said fibers arereacted with a cellulose cross-linking agent in the presence of a basesolution, the conditions of this reaction being such that the wettensile strength of the fibers is reduced below the dry strength of thefibers, the improvement which comprises applying to said textilematerial up to about 8% by weight of the base solution of an antioxidantselected from a group consisting of oxidizable inorganic salts, metalformaldehyde sulfoxylates, aldehydes, aromatic alcohols, aromaticamines, aliphatic amines, and condensation products of amines andaldehydes, and retaining said antioxidant on said textile materialduring the cross-linking reaction whereby the wet tensile strength ofthe fibers is not reduced to the same extent as would occur in thecross-linking reaction in the absence of said antioxidant.

2. A process according to claim 1 wherein said crosslinking agentcomprises divinyl sulfone.

3. A process according to claim 1 wherein said crosslinking agentcomprises 1,3-dichloropropanol-2.

4. A process of claim 3 where the base comprises sodium hydroxide.

5. A process of claim 4 wherein the effective concentration of the basicsolution in the textile material is from about 3 to about 30% by Weight.

6. An improved process according to claim 1 wherein said antioxidant isa readily oxidizable inorganic salt.

7. A process according to claim 6 wherein said antioxidant is dissolvedin an aqueous solution of said base and applied simultaneously with saidbase to said textile material.

8. A process according to claim 7 wherein the amount of said antioxidantadded to said basic solution is from 0.01% to 3% by weight of saidsolution.

9. A process according to claim 8 wherein said antioxidant is sodiumsulfite.

10. A process according to claim 8 wherein said antioxidant is sodiumthiosulfate.

11. A process according to claim 9 wherein said base is sodiumhydroxide.

12. A process according to claim 11 wherein said cross-linking agent isa mixture of dichloropropanols.

13. A process according to claim 12 wherein said textile material is acotton fabric.

14. In a process for imparting fiat drying properties to a textilefabric containing at least about 40% by weight of cellulosic fibershaving an average of at least about 1.8 free hydroxyl groups per glucoseunit, and wherein said textile material is impregnated with a solutionof an alkali metal hydroxide and has distributed thereon a quantitysufiicient to result in said cellulose fibers gaining from about 2% to4% in weight, of a cross-linking agent which results in cross-linkagesof from 3 to 10 carbon atoms in length under conditions whereby the wettensile strength of the fibers is reduced below the dry tensile strengthof the fibers, the improvement which comprises applying to said fabricup to about 8%, by weight of the solution of an alkali metal hydroxide,of an antioxidant selected from the group consisting of oxidizableinorganic salts, metal formaldehyde sulfoxylate, aldehydes, aromaticalcohols, aromatic amines, aliphatic amines and condensation products ofamines and aldehydes, and retaining said antioxidant on said fabricduring the cross-linking reaction, whereby at least the wet tensilestrength of the fibers is considerably improved.

over the wet tensile strength of fibers similarly treated but in theabsence of said antioxidant.

15. A process according to claim 14 wherein said antioxidant comprisessodium sulfite and is applied by being dissolved in said alkali metalhydroxide solution, and is applied in an amount equal to from 0.01% to0.3% by weight of said alkali metal hydroxide solution.

16. An improved method for imparting a pronounced wet memory to textilematerials such. as fabrics and yarns containing cellulosic fibers havingan average of at least about 1.8 free hydroxyl groups per unit whichcomprises distributing in and on said textile material water, an alkalimetal hydroxide, an anti-oxidant selected from the group consisting ofoxidizable inorganic salts, metal formaldehyde sulfoxylates, aldehydes,aromatic alcohols, aromatic amines, aliphatic amines and condensationproducts of amines and aldehydes, and a cellulose cross-linking agentsuch that said textile material contains a total amount of water equalto from about to 130% of the dry weight of said cellulose, an amount or"alkali metal hydroxide equal to from about 5% to 30% of the total waterpresent, an amount of anti-oxidant equal to from about 0.005% to 3.0% ofthe total amountof water present, and an amount of said cross-linkingagent equal to from 3% to 30% of the dry weight of said cellulose,conforming said textile material, immediately following the distributionof reagents thereon, to a selected configuration, enclosing said textilematerial to prevent loss of reagents, retaining said enclosed materialin said configuration until said cellu lose has gained from about 1% to4% in weight as a result of chemical modification, and thereafterwashing said textile material to remove unreacted reagents.

17. An improved method for imparting a pronounced wet memory to textilematerials, such as fabrics and yarns, containing cellulose fibers havingan average of at least about 1.8 free hydroxyl groups per glucose unitwhich'tcom prises distributing inand on said textile material water,sodium hydroxide, sodium sulfite, and a mixture of1,3-dichloro-2-propanol and 2,3-dichloro-1- propanol such that saidtextile material contains a total amount of water equal to/from 20% toof the dry weight of said cellulose, an amount of sodium hydroxide inexcess of that required to neutralize the hydrogen chloride eliminatedfromsaid dichloro-propanols and equal to from 5% to 15% of the .totalwater present, an amount of sodium sulfite equal to from 0.01% to 1% ofthe total Water present, and an-amount of saiddichloro-propanols equalto from 3% to 30% of the dry weight of said cellulose, conforming saidtextile material, immediately following the distribution of reagentsthereon, to a selected configuration, enclosing saidrtextile material toprevent loss of reagents, retaining said enclosed material in saidselected configuration until said cellulose has gained from about 1% to4% in weight as a result of chemical modification, and thereafterwashing said textile material to remove unreacted reagents.

References Cited by the Examiner UNITED STATES PATENTS v Jones '8133OTHER REFERENCES Marsh, John "11:v Mercerising, 1942, pp. 244-247.Mercerisation, editors of The Dyer and Calico Printer, 1903, pages -143.

NORMAN G. TORCHI N, Primii- Examiner.

MORRIS O. WOLK, A. LOUIS MONACELL,

, Examiners.

1. IN A PROCESS FOR IMPARTING FLAT DRYING CHARACTERISTICS TO A TEXTILEMATERIAL CONTAINING CELLULOSIC FIBERS HAVING AN AVERAGE OF AT LEASTABOUT 1.8 FREE HYDROXYL GROUPS PER GLUCOSE UNIT, WHEREIN SAID FIBERS AREREACTED WITH A CELLULOSE CROSS-LINKING AGENT IN THE PRESENCE OF A BASESOLUTION, THE CONDITIONS OF THIS REACTION BEING SUCH THAT THE WETTENSILE STRENGTH OF THE FIBERS IS REDUCED BELOW THE DRY STRENGTH OF THEFIBERS, THE IMPROVEMENT WHICH COMPRISES APPLYING TO SAID TEXTILEMATERIAL UP TO ABOUT 8% BY WEIGHT OF THE BASE SOLUTION OF AN ANTIOXIDANTSELECTED FROM A GROUP CONSISTING OF OXIDAZABLE INORGANIC SALTS, METALFORMALDEHYDE SULFOXYLATES, ALDEHYDES, AROMATIC ALCOHOLS, AROMATICAMINES, ALIPHATIC AMINES, AND CONDENSATION PRODUCTS OF AMINES ANDALDEHYDES, AND RETAINING SAID ANTIOXIDANT ON SAID TEXTILE MATERIALDURING THE CROSS-LINKING REACTION WHEREBY THE WET TENSILE STRENGTH OFTHE FIBERS IS NOT REDUCED TO THE SAME EXTEND AS WOULD OCCUR IN THECROSS-LINKING REACTION IN THE ABSENCE OF SAID ANTIOXIDANT.